Three-phase alternating current voltage regulator

Abstract

A three-phase AC voltage regulator is for adjusting a line voltage on transmission lines. The three-phase AC voltage regulator includes a sampling circuit, a reference-voltage circuit, a comparator, a switch, a power supply, and a compensator. The sampling circuit is for sampling the line voltage. The reference-voltage circuit is for receiving a line-to-line voltage from the transmission lines and generating a standard voltage. The comparator is for comparing the line voltage and the standard voltage to obtain a signal. The switch is for being turned on or off based on the signal. The power supply is for supplying various electric powers to the compensator. The compensator is for receiving the electric power and generating compensating voltages. The compensating voltages are used to compensate the line voltage.

1. A three-phase AC voltage regulator for adjusting a line voltage on transmission lines, the three-phase AC voltage regulator comprising:
 a sampling circuit for sampling the line voltage; 
 a reference-voltage circuit for receiving a line-to-line voltage from the transmission lines and generating a standard voltage; 
 a comparator for comparing the line voltage and the standard voltage to obtain a signal; 
 a power supply for supplying an electric power; 
 a compensator for receiving the electric power and generating compensating voltages to be used to compensate the line voltage; and 
 a switch for switching the electric power to the compensator based on the signal. 
 
   
   
     2. The three-phase AC voltage regulator according to  claim 1 , wherein the comparator comprises a first comparing unit for generating a first output voltage when the sampled voltage is greater than the standard voltage, and a second comparing unit for generating a second output voltage when the sampled voltage is smaller than the standard voltage. 
   
   
     3. The three-phase AC voltage regulator according to  claim 2 , wherein the comparator also comprises a first time-delay unit for delaying the first output voltage, and a second time-delay unit for delaying the second output voltage. 
   
   
     4. The three-phase AC voltage regulator according to  claim 3 , wherein the power supply comprises a positive voltage terminal for outputting a positive voltage, and a negative voltage terminal for outputting a negative voltage. 
   
   
     5. The three-phase AC voltage regulator according to  claim 4 , wherein the switch comprises a switching module connected to the comparator, the positive voltage terminal, and the negative voltage terminal. 
   
   
     6. The three-phase AC voltage regulator according to  claim 5 , wherein the switching module comprises a first relay for switching the positive voltage to the compensator, and a second relay for switching the negative voltage to the compensator. 
   
   
     7. The three-phase AC voltage regulator according to  claim 6 , wherein the first comparing unit comprises a first operational amplifier, and a noninverting input of the first operational amplifier is for receiving the sampled voltage, and an inverting input of the first operational amplifier is for receiving the standard voltage, and an output of the first operational amplifier is for outputting the first output voltage. 
   
   
     8. The three-phase AC voltage regulator according to  claim 7 , wherein the first comparing unit comprises a second operational amplifier, and a noninverting input of the second operational amplifier is for receiving the standard voltage, and an inverting input of the second operational amplifier is for receiving the sampled voltage, and an output of the second operational amplifier is for outputting a third output voltage. 
   
   
     9. The three-phase AC voltage regulator according to  claim 8 , wherein the first comparing unit comprises a third operational amplifier, and a noninverting input of the third operational amplifier is for receiving the third output voltage, and an inverting input of the third operational amplifier is for receiving the standard voltage, and an output is for outputting the second output voltage. 
   
   
     10. The three-phase AC voltage regulator according to  claim 9 , wherein the first time-delay unit comprises a first RC network and a first bipolar junction transistor, one end of the first RC network is connected to the output of the first operational amplifier, and the other end of the RC network is connected to a base of the first bipolar junction transistor. 
   
   
     11. The three-phase AC voltage regulator according to  claim 10 , wherein an emitter of the first bipolar junction transistor is connected to ground, and a collector of the first bipolar junction transistor is connected to the first relay. 
   
   
     12. The three-phase AC voltage regulator according to  claim 11 , wherein the second time-delay unit comprises a second RC network and a second bipolar junction transistor, one end of the second RC network is connected to the output of the third operational amplifier, and the other end of the RC network is connected to a base of the second bipolar junction transistor. 
   
   
     13. The three-phase AC voltage regulator according to  claim 12 , wherein an emitter of the second bipolar junction transistor is connected to ground, and a collector of the second bipolar junction transistor is connected to the second relay. 
   
   
     14. A three-phase AC voltage regulator for adjusting a line voltage on transmission lines, the three-phase AC voltage regulator comprising:
 a sampling circuit electrically connected to the transmission lines; 
 a comparator electrically connected to the sampling circuit; 
 a reference-voltage circuit electrically connected to the transmission lines to receive a line-to-line voltage and to generate a standard voltage to the comparator; 
 a switch electrically connected to the comparator; 
 a power supply electrically connected to the switch; and 
 a compensator electrically connected between the switch and the transmission lines. 
 
   
   
     15. The three-phase AC voltage regulator according to  claim 14 , wherein the comparator comprises an operational amplifier, and a noninverting input of the operational amplifier is electrically connected to the sampling circuit, and an inverting input is electrically connected to the reference-voltage circuit. 
   
   
     16. The three-phase AC voltage regulator according to  claim 14 , wherein the switch comprises a relay electrically connected to the comparator, the power supply, and the compensator. 
   
   
     17. The three-phase AC voltage regulator according to  claim 14 , wherein the compensator comprises a transformer, an adjustable transformer, and a motor, and the transformer and the motor are electrically connected to the adjustable transformer and the switch. 
   
   
     18. The three-phase AC voltage regulator according to  claim 14 , wherein the sampling circuit comprises a transformer, and a primary coil of the transformer is electrically connected to the transmission lines. 
   
   
     19. The three-phase AC voltage regulator according to  claim 18 , wherein the sampling circuit comprises a rectifier electrically connected to a secondary coil of the transformer, and a filter electrically connected to the rectifier. 
   
   
     20. The three-phase AC voltage regulator according to  claim 15 , wherein the comparator comprises a RC network and a bipolar junction transistor, and one end of the RC network is electrically connected to an output of the operational amplifier, and the other end of the RC network is electrically connected to a base on the bipolar junction transistor.